Some internal combustion engines, such as those with 6, 8 or even more cylinders can be designed to shut down or deactivate some cylinders during operating conditions where less than all cylinders are required to provide the instantaneous power requirements. For example, cruising at motorway/highway speed often requires only around 30% of available power while incurring significant inefficiencies through, for example, pumping losses. By deactivating one or more cylinders, the fuel consumption and engine emissions can be reduced while still providing the necessary power requirements. If more power is required, for example for acceleration or gradient climbing (e.g., hill climbing), the deactivated cylinders can be reactivated to provide the additional power. Some known approaches deactivate a single bank of cylinders within a V-configuration engine, while others deactivate selected ones of cylinders in a straight configuration engine. Such a technological approach may be called various names, including cylinder deactivation, Displacement on Demand™, Multi-Displacement System™, or Variable Cylinder Management™.
Such cylinder deactivation systems can be used in conventional internal combustion engine powered vehicles or in combination with electric hybrid vehicle power systems.
In some cylinder deactivation engine systems, a torque shock of sufficient magnitude so as to be noticeable by a vehicle occupant can occur at cylinder deactivation and/or activation events.
Example embodiments of the present invention resolve the above-noted, known disadvantages and drawbacks of known systems.